Finite-Momentum Antiferromagnetic Magnon Dynamics across the Morin Transition in Hematite
Abstract
Hematite (α-Fe2O3) is a prototypical antiferromagnetic platform for high-speed spintronics and magnonics, yet its finite-momentum magnon dynamics and spin-reorientation mechanism remain incompletely understood. Here we use low-wavenumber magneto-Raman spectroscopy to resolve both k=0 and finite-k sub-terahertz magnons in α-Fe2O3 across the Morin transition. We find that the limiting group velocity v0 remains nearly field independent, whereas the finite-k group velocity vg is strongly modified near the Morin and spin-flop transitions. By combining parallel- and transverse-field measurements with spin-wave modeling, we further extract the temperature-dependent Dzyaloshinskii--Moriya field HD and uniaxial anisotropy fields HK1 and HK2. We find that HD is weakly temperature dependent at approximately 2.0--2.3~T, while HK1 decreases rapidly and HK2 changes only weakly. This contrast drives the sign reversal of the effective anisotropy field and quantitatively accounts for the Morin transition. Our results establish low-wavenumber Raman spectroscopy as a quantitative probe of finite-momentum antiferromagnetic magnons and provide key material parameters for hematite-based magnonics.
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BibTeX
@misc{gong2026finitemomentum,
title = {{Finite-Momentum Antiferromagnetic Magnon Dynamics across the Morin Transition in Hematite}},
author = {Jiaqi Gong and Yuanzhe Tian and Jun Cui and Meiye Hou and Yuxuan Mu and Di Wang and Xiangang Wan and Di Wu and Qi Zhang},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2610.08030},
eprint = {2610.08030},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2610.08030},
}
RIS
TY - UNPB
TI - Finite-Momentum Antiferromagnetic Magnon Dynamics across the Morin Transition in Hematite
AU - Jiaqi Gong
AU - Yuanzhe Tian
AU - Jun Cui
AU - Meiye Hou
AU - Yuxuan Mu
AU - Di Wang
AU - Xiangang Wan
AU - Di Wu
AU - Qi Zhang
PY - 2026
DA - 2026/10/06
PB - arXiv
DO - 10.48550/arxiv.2610.08030
UR - https://arxiv.org/abs/2610.08030
AB - Hematite (α-Fe_2O_3) is a prototypical antiferromagnetic platform for high-speed spintronics and magnonics, yet its finite-momentum magnon dynamics and spin-reorientation mechanism remain incompletely understood. Here we use low-wavenumber magneto-Raman spectroscopy to resolve both k=0 and finite-k sub-terahertz magnons in α-Fe_2O_3 across the Morin transition. We find that the limiting group velocity v_0 remains nearly field independent, whereas the finite-k group velocity v_g is strongly modified near the Morin and spin-flop transitions. By combining parallel- and transverse-field measurements with spin-wave modeling, we further extract the temperature-dependent Dzyaloshinskii--Moriya field H_D and uniaxial anisotropy fields H_K1 and H_K2. We find that H_D is weakly temperature dependent at approximately 2.0--2.3~T, while H_K1 decreases rapidly and H_K2 changes only weakly. This contrast drives the sign reversal of the effective anisotropy field and quantitatively accounts for the Morin transition. Our results establish low-wavenumber Raman spectroscopy as a quantitative probe of finite-momentum antiferromagnetic magnons and provide key material parameters for hematite-based magnonics.
ER -